The effect of substituting Kenyan Serena sorghum for maize in broiler starter diets with different dietary crude protein and methionine levels

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Abstract

the semi-arid regions to help alleviate a feed and food shortage. Sorghum is well suited to
cultivation in areas that are too dry or too hot for the production of other cereals. Although
sorghum is similar in composition to maize, brown sorghum contains the anti-nutritive factor
tannin. The possibility of overcoming any detrimental effects of sorghum tannin on the growth
rate and feed efficiency of broiler chicks by supplementing the diet with intact crude protein (CPl
or D,L-methionine (Met) was studied in two Cweek feeding trials of 280 chicks each. In each trial
the effects of feeding maize or brown sorghum were compared under three dietary specifications
(control, increased CP, increased Met). In both trials, the tannin content of the control brown
sorghum diet was 1.3% catechin equivalents (dry matter basis). A seventh diet, with dietary
specifications similar to the control diets, was included in each trial for comparison with the six
main diets. In Trial 1 the seventh diet contained a combination of white and brown (w/b)
sorghum (SO/SO, w/w) as the main energy source while in Trial 2 the main energy source of the
seventh diet was white sorghum alone. In both trials there were no significant differences in final
body weight among the three control diets (770.2, 759.0, and 753.0 g for the broilers on the
maize, brown sorghum, and w/b sorghum diets in Trial 1; and 822.7, 764.8, and 827.2 g for the
broilers on the maize, brown sorghum, and white sorghum diets in Trial 2). In addition, there were
no significant differences in feed conversion ratio (FCR) between the maize and brown sorghum
fed broilers (2.01 vs. 2.03 in Trial 1; and 1.82 vs. 1.94 in Trial 2). In Trial 2, however, the FCR
for the broilers receiving the white sorghum diet (1.73) was significantly lower than for those receiving the brown sorghum control diet (1.94), but not significantly different from those receiving the maize control diet (1.82). There was no effect of Met supplementation on final body weight or FCR in either trial. In Trial 1, increasing dietary CP content had no effect on final body weight or FCR for both the maize and brown sorghum fed broilers. In Trial 2, however, increasing
the dietary CP content resulted in significantly lower final body weights (708.2 vs. 822.7 g) and
higher FCR (2.06 vs. 1.82) for the maize fed broilers. The results of this study suggest that high
tannin sorghum can be substituted for white maize in broiler starter diets with no significant
adverse effects on growth or feed efficiency. The dietary treatments of increased CP or Met levels,
which have been reported to be successful at overcoming the detrimental effects of sorghum
tannins, were not required.
A leg abnormality previously reported by other sorghum researchers was observed in both
trials but the incidence and severity were low. Broilers receiving maize based diets with increased
Met were most affected suggesting that the abnormality is related to increased Met and not to
tannins.